The invention relates to a medical access device for creating an access for a minimally invasive intervention, with a hollow body assembled from at least two parts along the longitudinal edges thereof, wherein each part has a distal body portion and, at an angle to the latter, a proximal body portion, and wherein projections present on the longitudinal edges engage with recesses on an opposite longitudinal edge.
A medical device of this kind is known from EP 2 228 024 A1.
In a first position, the at least two parts are assembled such that the respective distal body portions form an approximately rod-shaped distal body. In this position, the medical device can be placed, for example, on an incision in the skin of an abdominal wall and can be driven through the abdominal wall into the abdominal cavity. In this state of assembly, the medical device thus functions as a trocar sleeve of a trocar, which is used for a laparoscopic intervention.
The proximal body portions, which are each angled laterally in relation to the respective distal body portions, extend to the sides from this assembled distal body and project above the skin or the abdominal wall. These proximal body portions are then pivoted such that they join together to form a proximal hollow body. In this process, the proximal body portions present in the abdominal space are pivoted laterally away from each other. A sealing cap is then fitted onto the proximal hollow body.
In this pivoting movement, the mutually opposite longitudinal edges of the bodies roll along each other in the curved transition area between the respective distal body portion and the respective proximal body portion. This rolling movement is guided by projections present on the longitudinal edges, which projections can engage in corresponding recesses on an opposite longitudinal edge.
These projections can be knobs or tongues that engage in corresponding depressions or grooves in the opposite longitudinal edges.
This arrangement of knobs or groove and tongues not only guides this rolling movement but also prevents the two parts from separating from each other transversely with respect to the surface of the longitudinal edges.
At the same time, the intensive interlocking of these toothing features ensures a relatively gas-tight seal along the longitudinal edges of the joined-together proximal body portions. In this way, it is possible, as is customary in laparoscopic surgery, to introduce an insufflation gas into the abdominal space through the proximal hollow body, which is formed by the two proximal body portions and is sealed off proximally by the cap, in order to inflate the abdominal space.
A particular advantage of the device is that a surgical instrument pushed through the latter can be tilted to and fro within a very large angle range. For the operating surgeon, this opens up a wide operating field for the surgical instruments that are pushed through the device, e.g. endoscopes, scissors, forceps and the like, for performing a surgical intervention.
In practice, it has been found that, when surgical instruments are extremely tilted and correspondingly oriented, they can have a tendency to move the two joined-together proximal body portions slightly away from each other as a result of the leverage exerted by the tilted instrument. This leverage acts in a proximal end area of one proximal body portion at the one side and in a distal end area of the adjacent proximal body portion at the other side. It has been observed that considerable gas losses occur as a result of gas escapes via the longitudinal edges of the joined-together proximal body portions, even when these are moved away from one another only by fractions of millimeters.
A vaginal speculum is known from German Utility Model G 78 01 125.3 and is composed of two shell-shaped parts, wherein each part has a distal body portion and, at an angle thereto, a proximal body portion.
In the area of the curvature, that is to say of the transition from the respective distal body portion to the proximal body portion, the two shell-shaped parts are firmly connected to each other by a joint. When the distal body portions are placed against each other, the speculum can be inserted into the vagina. When the proximal body portions are joined together to form a hollow body, the already inserted distal body portions then spread the vagina open. The physician can then make suitable visual observations through the vaginal speculum designed as a hollow body.
A locking device is provided to ensure that, during the observation, the two proximal body portions do not spread apart from each other again as a result of the restoring force of the vaginal tissue.
On one of the two proximal bodies, the locking device has tabs which protrude in a circumferential direction away from the longitudinal edges thereof. The tabs, in a cross section perpendicular to the longitudinal edges, widen in a wedge shape starting from the free end. The tip of the wedge extends in a radial direction in view of the longitudinal axis of the speculum. On the opposite proximal body portion, recesses are provided on the inner or the outer face of the wall, into which recesses the tabs fit and the wedge shape ensure a locking engagement.
For this purpose, however, the geometry and shape of the tabs must be such that they have a degree of elasticity allowing them to bend radially, in order to be able to be driven into the recesses on the inner or outer face of the wall surface of the other proximal body portion.
To release the locking mechanism, the operator has to exert a strong radially inward pressure so as to slightly deform the hollow body composed of the two locked proximal body portions, to an extend that a wedge-shaped tab can escape from the recess on the wall. In the case of a vaginal speculum, which is substantially larger than the device of the present application and which has a considerable wall thickness and is in most cases made of metals, an elastic tab construction of this kind and recesses on the wall of the other proximal body portion can be provided.
In the case of substantially smaller hollow bodies with thinner walls, like the device of the present application, such a construction will not be able to work in a reliable manner. There would be the danger of extremely tilted instruments causing deformations that allow the wedge-shaped tab to escape from the recess on the inner wall.
It is therefore an object of the present invention to provide a medical access device having a locking mechanism which prevents a release of the locking by tilted instruments inserted in the medical access device.